This program converts a set of files containing raw instrumental magnitude measurements (one instrumental magnitude per file) into a single file, in which measurements of the same star (in different passbands) have been merged.
The positions of stellar detections in each passband are compared to each other, and any objects which are within matchrad arcseconds are considered a match. If there are several objects within this radius, the one closest to the detection in the first passband is chosen. By default, in order for stars to appear in the merged output file, they must have valid measurements in all passbands. A value of "99" for magnitude or uncertainty in magnitude, in any passband, disqualifies a star. However, the user may permit "orphan" stars to be retained in the output by using the orphans option on the command line; see instructions below.
The result of the collate program is a set of stars with good measurements in all passbands. These may then be fed as input to the photom program for calibration.
collate passband= coofile astfile passband= coofile astfile [...] matchrad= jd= lat= long= exptime= [orphans=] [outfile=]
passband is name of a passband, such as V or I The two following args are required: coofile is the name of a ".coo" data file for that passband contains info on each detected star's shape astfile is the name of a ".ast" data file for that passband contains (RA, Dec) and instrumental mag for each detected star (there can be 2-4 sets of "passband= coofile astfile" args, each describing data in a different passband) matchrad radius (in arcseconds) to use when matching stars detected in each passband against those in other passbands jd Julian Date when image was taken lat latitude of observations (degrees North of equator) long longitude of observations (degrees West of Greenwich) exptime exposure time (in seconds). Is assumed to be the same for all passbands orphans (optional) what should we do with stars not detected in all passbands? By default, or if orphans=0, we discard them. But if orphans=1, we retain them and pass them through to output. outfile (optional) name of output file stdout used by default
Here's an example of the input file formats. Lines which start with a pound character "#" will be ignored. Unlike the photom program, which takes command-line arguments to describe the format of the input files, the collate program currently demands that the input files have formats which adhere strictly to the descriptions below. Future versions of the program may have a mechanism which allows some flexibility.
# ID xc yc peak FWHM round sharp 1 6.24 575.46 858 2.471 0.046 0.860 2 7.10 217.70 1341 2.610 0.015 0.620 3 21.73 1747.02 1304 1.784 0.355 0.867 4 24.94 1471.74 3970 2.259 0.154 0.834The columns must contain
At the moment, the ID, FWHM, roundness, and sharpness values are stored in a data structure for each star, and the other values are ignored. In addition, the program doesn't use the stored values at the moment ... but future versions might allow the user to place limits on these parameters for accepting stars as valid.
# ID RA Dec sky skyerr mag magerr qual 1 228.50650 0.76982 364 10.27 15.630 0.059 1 2 228.50063 0.00148 384 12.47 14.370 0.020 0 3 228.48867 3.28749 355 8.72 15.659 0.060 3 4 228.47779 2.69573 355 9.50 14.152 0.017 0The columns must contain
The ID, RA, Dec, mag, magerr, and quality values for each star are stored in a structure, and all of them are used by the program. The sky and skyerr fields are read, but then discarded.
We could run the program with a command line like this (I've split the line to keep it from wrapping around):
photom passband=V field1v.coo field1v.ast passband=I field1i.coo field1i.ast matchrad=5 jd=2451659.826 lat=43.43 long=92.33 exptime=60.0 outfile=field1
We create a single output file. If the user doesn't provide an outfile= argument on the command line, the output is sent to stdout. If he does supply an outfile= argument, the output is placed in a file of the given name. It has a format like this:
# ID RA Dec JD air mag magerr mag magerr qual 88 224.25832 0.46297 2451659.8260 1.402 V 17.897 0.047 I 17.008 0.031 0 148 224.26077 1.97270 2451659.8260 1.369 V 18.336 0.068 I 16.672 0.023 1 94 224.27842 1.56057 2451659.8260 1.378 V 17.981 0.050 I 16.651 0.022 257 32 224.26298 1.00923 2451659.8260 1.333 V 19.304 0.126 I 99.000 99.000 2048
The columns have the following meanings:
Note that the final star in the list above was detected only in the V passband. The user must have given the command-line option orphans=1 in order for this star to be passed through to the output.
There may be up to 4 different passbands included in the merged output. Each passband has three columns of data.
Last modified Mar 27, 2005, by MWR.